The present invention concerns package padding material as defined in the preamble to claim 1. The invention further concerns an apparatus, defined in the preamble to Claim 11, for forming package padding material.
In prior art e.g. through the reference U.S. Pat. No. 5,203,761 an apparatus is known which has been arranged to form paper into continuous and web-like package padding material which comprises superimposed paper courses. The paper courses present a continuous series of successive and side-by-side eminences embossed in the paper courses. This serves the purpose of endowing the package padding with a cellular padding structure, and thus it increases the bulk of the paper web substantially. In the apparatus of the reference all paper course webs are run superimposed through between shaping rolls, the paper courses thus being pressed between said shaping rolls, whereby a cellular relief pattern is produced in them. Hereafter, the paper courses are separated and conducted by mutually different paths to combining rolls so that the eminences in the paper courses will be offset relative to each other so that they are no longer in register when they are once more superimposed, whereby a multiply cellular structure is obtained. The combining rolls are not arranged to break up the structure of the package padding web.
The problem with the apparatus and package padding known in the art is that, in practice, the individual paper courses of the paper padding tend to become detached from each other, and this will substantially impair the usability of the package padding and retention of its fluffiness. This is because keeping the package padding of prior art as a fluffy, padding structure would imply that in no situation whatsoever the paper courses would become mutually displaced into a relative position in which they were together pressed and in which the eminences and depressions of the paper courses are in register and will settle one into the other.
The previously known package padding and apparatus are further embarrassed by the problem that all paper courses are passed through the same pairs of rolls, as a result of which the structure of the package padding is similar throughout over the whole of its area, and this for instance hampers any attempts to fold the paper padding double. Detachment of the paper courses from each other is specifically the particular problem encountered when folding the material.
The apparatus known in the art moreover poses the problem that the paper courses are taken from one single paper roll on which several courses of paper webs have been wound, superimposed in special manner. The drawback here is that the operator cannot freely select any paper roll which he may desire to use in the machine.
A further problem associated with the apparatus known in the art and with paper padding therewith produced is that in practice the package padding is highly susceptible to flattening on being pressed, losing its padding property.